According to a blog post on the Windows Team Blog, there will be two editions of Windows 8 for x86/64 processors: Windows 8 and Windows 8 Pro.

Windows 8 is the consumer SKU. It will include the updated Windows Explorer, Task Tak Manager, better multi-monitor support and the ability to "switch languages on the fly," which previously was only available to those purchasing the Enterprise and Ultimate Editions of Windows .

Windows 8 Pro is for tech enthusiasts and business/technical professionals, and adds features for encryption, virtualization, PC management and domain connectivity. The Windows Media Center functionality will be available as an add-on to Windows 8 Pro, known as the "Media Pack."

Microsoft is naming the Windows on ARM (WOA) version Windows RT. Yes, another WinRT -- which is the Windows Runtime (WinRT), the new Windows Runtime which is at the heart of the Metro-Style side of Windows 8. The WinRT version is for WOA tablets and PCs only. I guess that means Windows 8 on Intel and AMD processors fall under the two SKU rule: It will be either Windows 8 or Windows 8 Pro if you are gravitating toward one of those devices due out later this year.

Update: As Paul Thurrott notes on the Windows SuperSite, there are actually four SKUs, not three. There also will be an Enterprise SKU of Windows 8.